﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;

namespace PeekService
{
    public class DecryptService
    {
         /// <summary>
            /// 构造方法
            /// </summary>
        public DecryptService()
        {}
            private const string KEY = "PeekKeyabc1234567654321ABC";
            /// <summary>
            /// 使用缺省密钥字符串加密
            /// </summary>
            /// <param name="original">明文</param>
            /// <returns>密文</returns>
            public static string Encrypt(string original)
            {
                return Encrypt(original, KEY);
            }
            /// <summary>
            /// 使用缺省密钥解密
            /// </summary>
            /// <param name="original">密文</param>
            /// <returns>明文</returns>
            public static string Decrypt(string original)
            {
                return Decrypt(original, KEY, System.Text.Encoding.Default);
            }
            /// <summary>
            /// 使用给定密钥解密
            /// </summary>
            /// <param name="original">密文</param>
            /// <param name="key">密钥</param>
            /// <returns>明文</returns>
            public static string Decrypt(string original, string key)
            {
                return Decrypt(original, key, System.Text.Encoding.Default);
            }
            /// <summary>
            /// 使用缺省密钥解密,返回指定编码方式明文
            /// </summary>
            /// <param name="original">密文</param>
            /// <param name="encoding">编码方式</param>
            /// <returns>明文</returns>
            public static string Decrypt(string original, Encoding encoding)
            {
                return Decrypt(original, KEY, encoding);
            }
            /// <summary>
            /// 使用给定密钥加密
            /// </summary>
            /// <param name="original">原始文字</param>
            /// <param name="key">密钥</param>
            /// <param name="encoding">字符编码方案</param>
            /// <returns>密文</returns>
            public static string Encrypt(string original, string key)
            {
                byte[] buff = System.Text.Encoding.Default.GetBytes(original);
                byte[] kb = System.Text.Encoding.Default.GetBytes(key);
                return Convert.ToBase64String(Encrypt(buff, kb));
            }

            /// <summary>
            /// 使用给定密钥解密
            /// </summary>
            /// <param name="encrypted">密文</param>
            /// <param name="key">密钥</param>
            /// <param name="encoding">字符编码方案</param>

            /// <returns>明文</returns>
            public static string Decrypt(string encrypted, string key, Encoding encoding)
            {
                byte[] buff = Convert.FromBase64String(encrypted);
                byte[] kb = System.Text.Encoding.Default.GetBytes(key);
                return encoding.GetString(Decrypt(buff, kb));
            }
            /// <summary>
            /// 生成MD5摘要
            /// </summary>
            /// <param name="original">数据源</param>
            /// <returns>摘要</returns>
            public static byte[] MakeMD5(byte[] original)
            {
                MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
                byte[] keyhash = hashmd5.ComputeHash(original);
                hashmd5 = null;
                return keyhash;
            }


            /// <summary>
            /// 使用给定密钥加密
            /// </summary>
            /// <param name="original">明文</param>
            /// <param name="key">密钥</param>
            /// <returns>密文</returns>
            public static byte[] Encrypt(byte[] original, byte[] key)
            {
                TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
                des.Key = MakeMD5(key);
                des.Mode = CipherMode.ECB;

                return des.CreateEncryptor().TransformFinalBlock(original, 0, original.Length);
            }

            /// <summary>
            /// 使用给定密钥解密数据
            /// </summary>
            /// <param name="encrypted">密文</param>
            /// <param name="key">密钥</param>
            /// <returns>明文</returns>
            public static byte[] Decrypt(byte[] encrypted, byte[] key)
            {
                TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
                des.Key = MakeMD5(key);
                des.Mode = CipherMode.ECB;

                return des.CreateDecryptor().TransformFinalBlock(encrypted, 0, encrypted.Length);
            }

            /// <summary>
            /// 使用给定密钥加密
            /// </summary>
            /// <param name="original">原始数据</param>
            /// <param name="key">密钥</param>
            /// <returns>密文</returns>
            public static byte[] Encrypt(byte[] original)
            {
                byte[] key = System.Text.Encoding.Default.GetBytes(KEY);
                return Encrypt(original, key);
            }

            /// <summary>
            /// 使用缺省密钥解密数据
            /// </summary>
            /// <param name="encrypted">密文</param>
            /// <param name="key">密钥</param>
            /// <returns>明文</returns>
            public static byte[] Decrypt(byte[] encrypted)
            {
                byte[] key = System.Text.Encoding.Default.GetBytes(KEY);
                return Decrypt(encrypted, key);
            }

    }
}
